Abstract:
Scientists have used nanotechnology to turn paper into a sensor that can detect toxins in drinking water. The China-US team dipped normal filter paper into a solution containing carbon nanotubes — which can conduct electricity — and antibodies to microcystin-LR, a common and dangerous toxin.

They dried the paper and repeated the process until enough nanotubes were present to render it conductive.

When the paper is dipped in contaminated water, the toxin binds to the antibodies and affects the conductivity of the nanotubes in the paper by separating them from each other. This change in conductivity is detected by a current-measuring device.

Lead researcher Nicholas Kotov, of the University of Michigan, United States, told SciDev.Net that the test is 'fast, sensitive and simple'. He said he envisaged that it could be engineered into a matchbook-sized device to test water on the spot.